Facile Ar−CF₃ Bond Formation at Pd. Strikingly Different Outcomes of Reductive Elimination from [(Ph₃P)₂Pd(CF₃)Ph] and [(Xantphos)Pd(CF₃)Ph]

Facile and highly selective perfluoroalkyl-aryl reductive elimination from a metal center (Pd) has been demonstrated for the first time. At temperatures as low as 50-80 degrees C, [(Xantphos)Pd(Ph)CF3] undergoes remarkably clean decomposition to produce CF3Ph in high yield and selectivity. In contrast, analogous trifluoromethylpalladium aryls stabilized by rigid cis-chelating ligands such as dppe are completely unreactive at temperatures up to 130-140 degrees C. Decomposition of [(Ph3P)2Pd(Ph)CF3] in the presence of PhI in benzene at 60 degrees C does not produce PhCF3 but rather leads to [(Ph3P)2Pd(Ph)I] and [Ph4P]+[(Ph3P)Pd(CF3)3]- in a 2:1 ratio with high selectivity.